Evening Edge

Recent headlines advised consumers to put down their water bottles and let thirst be their guide.

This caught my attention, so I tracked down the source to see what the fuss was all about. It turns out that the headline-generating editorial, "Just Add Water," was released in advance of publication in a nephrology (kidney) journal.

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The short editorial did not warn of the dangers of drinking too much water, but said that the claims on the Internet that water improves your skin tone, leads to weight loss and clears toxins is not well substantiated and water is not the panacea that it is often made out to be.

So, should you abandon your gallon water jug and drink only when thirsty?

I referred to the Institute of Medicine guidelines that say an average non-exercising adult man needs about 125 ounces and women need 90 ounces of fluid a day to maintain health. Fluids do not have to be from water. About 80 percent of fluids come from liquids and that includes all liquids — juice, soft drinks, tea and coffee, all of which contribute to our fluid needs. The other 20 percent comes from food — fruits and vegetables are especially good sources of water.

But the guidelines are not for the active person. We know that active people need more fluids, especially when exercising in hot, humid conditions.

When exercising, thirst is not a good indicator of fluid need. Active people should use other cues to stay well-hydrated. Weighing before and after activity can give you a quick estimate of fluid loss (for every pound lost, drink two to three cups or 18 to 24 ounces of fluid) or watch urine color (if color is dark, you are probably dehydrated).

The editorial concludes: "There is no clear evidence of benefit from drinking increased amounts of water ... there is simply a lack of evidence in general."

So, students sitting in classes all day probably don't need their gallon water jugs (maybe my students who drink huge amounts of water are trying to find a way to take more frequent bathroom breaks to get out of my classroom), but if you are running, cycling, playing team sports, taking aerobic classes or just working out, staying hydrated can enhance performance and keep you safe from heat illnesses.